When producing semiconductor components, it is necessary in many cases to produce a foreign material layer, that is to say a material layer which is not composed of a semiconductor material, in a semiconductor body. Such material layers are dielectric layers, for example, which are used as capacitor dielectric in capacitors or as gate dielectric or field plate dielectric in MOS transistors. Such material layers can furthermore also be composed of a conductive material such as, for example, a metal or a metal-semiconductor compound.
In order to produce a foreign material layer extending in a vertical direction in a semiconductor body, it is possible to produce a trench that is subsequently filled with the desired foreign material. However, producing very thin layers which additionally extend deeply into the semiconductor body is difficult by using such a method since trenches having a high aspect ratio (ratio of depth to width of the trench) would have to be produced for this purpose. Such trenches having a high aspect ratio either can only be produced in a costly manner or cannot be economically produced at all above a specific aspect ratio, for example, greater than 1000:1.
In vertical power components, for example, which include a drift zone and a drift control zone arranged adjacent to the drift zone, which are dielectrically insulated from one another by a drift control zone dielectric, very thin foreign material layers are required as drift control zone dielectric. In these components, the drift zone—and also the drift control zone—serves for taking up a reverse voltage when the component is driven in the off state, and the drift control zone serves for controlling a conducting channel in the drift zone when the component is driven in the on state. In this case, the thickness of the drift control zone dielectric should be as small as possible in order to enable the conducting channel to be controlled effectively. Furthermore, the drift control zone dielectric should extend in a vertical direction over the entire length of the drift zone.